JPH1053630A - Production of abs resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an ABS resin, excellent in physical and mechanical properties such as impact strength, elastic modulus, yield point and ultimate tensile strength and having high glossiness in combination. SOLUTION: This method for producing an ABS resin comprises the following steps (a), (b), (c), (d) and (e): (a) preparing a solution comprising an S-B type di-block linear rubber dissolved in a monomer mixture containing styrene and acrylonitrile, (b) feeding at least one preformed ABS resin in which rubber particles contained in a polymer matrix have >1.5μm average volume diameter to the solution in the step (a), (c) dissolving the preformed ABS resin in the solution in the step (a), (d) continuously feeding the resultant solution to a polymerizing reactor for the ABS resin and (e) polymerizing the final solution and producing the ABS resin having a multimodal morphology.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an ABS resin.

More specifically, the present invention relates to a continuous bulk solution method for producing an ABS polymer in which the size of rubber particles contained in a polymer matrix exhibits a multimodal distribution.

More specifically, the present invention relates to an ABS resin having excellent physical mechanical properties such as impact strength, elastic modulus, yield point, and ultimate tensile strength, and having high glossiness. But also.

[0004]

BACKGROUND OF THE INVENTION Aromatic vinyl copolymers reinforced with rubbers, especially diene rubbers, are known in the marketplace and are representative of a group of well-known technopolymers that are widely described in the literature. A specific example of such a copolymer is, for example, a styrene / acrylonitrile copolymer comprising rubber particles, such as polybutadiene, dispersed in a polymeric matrix, commonly known as ABS resin.

[0005] These copolymers can be produced in a continuous or batch manner by various polymerization methods such as emulsification, bulk, solution or a combination of bulk and suspension.

[0006] Continuous bulk solution polymerization processes are known and are described, for example, in US Patent Nos. 2,694,692, 3,243,
481, 3,658,946 and EP-A-400,479. The method comprises the steps of dissolving a rubber substance in an aromatic vinyl monomer or monomer mixture, adding a radical polymerization initiator and optionally an inert diluent, and polymerizing the resulting solution. Immediately after the start of the polymerization reaction, the solution in which the rubber substance is dissolved in the monomer mixture is divided into two phases, and the first phase consisting of the solution in which the rubber substance is dissolved in the monomer mixture and the solvent first forms a continuous phase. While a second phase consisting of a solution of the resulting copolymer in the monomer mixture and the solvent is dispersed in the first phase in the form of droplets.

As the polymerization, ie, the conversion, proceeds, the first phase is consumed and the amount of the second phase increases. As soon as the volume of the second phase equals the volume of the first phase, a phase change, commonly called phase inversion, occurs. When this phase inversion occurs,
Drops of the rubber solution are formed in the polymer solution. on the other hand,
These droplets of the rubber solution encapsulate the microdroplets in the phase that has just become the continuous phase of the polymer. During the process, rubber may be grafted on some of the polymer chains.

[0008] The polymerization is usually carried out in several steps. In the first step of the polymerization, called prepolymerization, a solution of the rubber in the monomer or monomer mixture is polymerized until it reaches a conversion at which phase inversion occurs. The polymerization is continued until the desired conversion is achieved.

This bulk solution polymerization makes it possible to produce aromatic vinyl copolymers in which the rubber is distributed in the polymer matrix in the form of particles, with a balance between physical mechanical properties and high gloss. However, in this polymerization method, at least in the case of an ABS copolymer, it is not possible to obtain characteristic values generally possessed by a product obtained by an emulsion synthesis method.

Various attempts have been made to try and improve the balance between the physico-mechanical properties and the glossiness of ABS, and are described in the literature. For example, as described in U.S. Pat. Nos. 4,421,895, 4,587,294, 4,639,494, and EP 277,687. Attempts have been made to select from low-viscosity rubber or block rubber (radial or branched). Another attempt is to obtain an ABS resin in which the rubber particles are bimodally distributed.

[0011] European Patent Application Publication No. 412,801
The article describes a process for producing rubber-reinforced copolymers (HIPS and ABS) with a bimodal distribution of rubber particles by a continuous bulk solution method.
In this method, the conversion is 10 to 50% of the initial monomer.
Are separately formed in two side-by-side plug-flow reactors.

The first prepolymer has a size of 0.0
Rubber particles of 5 to 1.5 micrometers are included, and the second prepolymer includes rubber particles of 0.7 to 10 micrometers in size. The two prepolymers are continuously discharged from the respective reactors, mixed in appropriate proportions and, in two or more reactors arranged in series, until the desired conversion is reached (65%).
(-80%). Thereafter, the solvent and unconverted monomers are removed by devolatilization.

The ratio of the two prepolymer streams is:
The rubber particles from the first prepolymer should be such that the rubber content of the final product is 50-95% by weight. The polymer obtained in this way is more mechanically agitated with a single extractor,
Excellent balance between mechanical properties and glossiness.

This method is particularly advantageous for producing high-impact polystyrene having a high resilience value and a high gloss. On the other hand, a significant resilience value is not obtained for ABS resin, so that it is too low. It has not proven to be advantageous. In addition, the specification of this patent application contains AB
Regarding the S resin, the value of glossiness, which is a basic parameter in the evaluation of the ABS resin, is not shown.

[0015] A further disadvantage of the above method, in particular of the production of ABS resin, is that in the case of a conventional plant layout, at least one more polymerization reactor must be added. It is also necessary to perform process control over the morphology formed, especially at the stage of mixing the two prepolymers. Any possible production upset in this part of the plant will cause irreparable damage to the performance of the product.

[0016]

SUMMARY OF THE INVENTION We have developed a method for producing an ABS copolymer having a bimodal structure or a multimodal structure, which has an excellent balance between gloss and mechanical properties. A new method that overcomes the shortcomings was found.

Accordingly, the present invention provides the following a), b),
The present invention relates to a method for producing ABS, comprising the steps c), d) and e), wherein the size of rubber particles contained in the polymer matrix shows a multimodal distribution.

A) a step of preparing a solution comprising an SB type two-block linear rubber dissolved in a monomer mixture containing styrene and acrylonitrile; b) rubber particles contained in a polymer matrix:
Supplying at least one preformed ABS resin having an average volume diameter greater than 5 micrometers to the solution of step (a); c) dissolving the preformed ABS resin in the solution of step (a). D) continuously feeding the solution thus obtained to a polymerization reactor for ABS resin, and e) polymerizing the final solution to produce an ABS having a multimodal morphology.

[0019]

SUMMARY OF THE INVENTION A process according to the present invention comprises a continuous bulk solution ABS comprising two or more plug flow reactors and one or more devolatilizers arranged in series. It can be carried out using a conventional plant for polymerization. This type of plant and its related manufacturing method is described in U.S. Pat.
No. 4,692, No. 3,243,481, No. 3,65
8,946, and European Patent Application Publication No. 400,
No. 479, each specification.

In the method according to the invention, the solution of step (a) is prepared using a two-block linear rubber of the SB type. Here, S represents an average molecular weight (Mw) of 5,000 to 50, obtained from an aromatic vinyl monomer such as styrene.
000 represents a non-elastomeric polymer block, while B represents an elastomeric polymer block having an average molecular weight (Mw) of 2,000 to 250,000 obtained from a conjugated diene such as butadiene. The amount of the S block in such rubber is 5 to 15% by weight of the entire SB rubber.

The SB rubber used in the method of the present invention is AB
In the method of producing the S resin by the bulk solution method, it has a property of giving a copolymer with rubber particles having an average volume diameter of 0.1 to 1.5 micrometers.

The solution of step (a) is prepared in the usual manner by dissolving the diblock rubber at room temperature or at a temperature below 100 ° C. in the monomer mixture. AB
The appropriate amount of rubber in the polymerization step of the S resin is 5 to 5
30% by weight, preferably 10 to 20% by weight.

The monomer mixture acting as a solvent for the diblock rubber comprises styrene and acrylonitrile. In this mixture, the amount of acrylonitrile is 5-40% by weight, preferably 15-35% by weight,
In contrast, the amount of styrene is 95-55% by weight, preferably 85-65% by weight. In some cases, a portion of the styrene is reduced to 50% by weight with other aromatic vinyl monomers such as, for example, α-methylstyrene, vinyltoluene, chlorostyrene, etc. It may be replaced until. A part of acrylonitrile is replaced by another acrylic monomer such as a monomer selected from, for example, an alkyl ester of acrylic acid or methacrylic acid (the alkyl group has 1 to 8 carbon atoms), and is replaced by up to 50% by weight. be able to.

The solvent base may contain, besides the monomer, a diluent selected from aromatic hydrocarbons which are liquid at the polymerization temperature. Examples of diluents include toluene, ethylbenzene, xylene, or mixtures thereof. Alternatively, a mixture of a non-polar compound, for example one or more of the above aromatic hydrocarbons, and a polar substance can be used as the solvent. The polar component refers to an organic compound composed of carbon and hydrogen and containing one or more hetero atoms such as oxygen and nitrogen in a molecule. Such derivatives are preferably aliphatic and saturated and liquid at the polymerization temperature, and if the molecule is not symmetric, the dipole moment value is 3 ×
It is characterized by exceeding 10 ^-30 Cm. Symmetric molecules such as dioxane are also included in this group. Examples of polar components are cyclohexanone, methyl ethyl ketone, diethyl ketone, acetonitrile, propionitrile, butyronitrile, ethyl acetate, butyl acetate, tetrahydrofuran, dioxane and the like. Of these, acetonitrile and propionitrile are preferred. The amount of polar component in the solvent mixture can vary within the range of 1 to 99% by weight, preferably 5 to 50% by weight.

The average volume diameter of the rubber particles contained in the polymer matrix is greater than 1.5 micrometers;
At least one preformed ABS resin, which is characterized, for example, by a size of 3 to 15 micrometers, is added according to the invention to the solution obtained by dissolving the diblock rubber in the monomer mixture. The amount of preformed ABS added is such that the preformed ABS is 0.5% of the final product.
It is an amount to be と 15% by weight.

The preformed ABS resin is preferably one obtained by continuous bulk polymerization or bulk suspension polymerization. The ABS resin has a rubber phase content of 20% by weight or more.
MFI (ASTM D1)
238) is 5 g / 10 min or more, and 12.7 mm
Impact Strength of Test Samples (ASTM D256)
Is 80 J / m or more.
These are also available on the market, for example,
There is a product of the applicant sold under the trade name "SINKRAL Series X2000".

The ABS of the present invention, which exhibits a multimodal distribution of rubber particles in size, can be prepared by conventional techniques used to produce impact-resistant crosslinked polymers, such as polymerization by bulk, solution, or bulk suspension methods. Even if the production can be tentatively performed, the advantage becomes more apparent when the polymerization is carried out by a continuous bulk solution method.

In this polymerization technique, rubber and preformed ABS resin are dissolved in monomers in the presence of a suitable solvent. The solvent is a monomer and rubber and the preformed A
Present in an amount of 0 to 100% by weight based on the total of BS,
The obtained solution is subjected to polymerization in the presence of an initiator.

The polymerization is usually carried out in two or more plug-flow, vertical, tubular, stirred reactors arranged in series. Vertical tubular reactors having a length / diameter ratio of more than 2, preferably 3 to 10, are preferred.

Each reactor is maintained at a pressure higher than the pressure at which the supplied components evaporate. Such pressures are typically 0.1
5-5 bar and the temperature is 70-170 ° C.

The polymerization conversion at the outlet of the first reactor is preferably from 20 to 60% by weight of the monomers, preferably from 25 to 50% by weight, and the polymerization is completed in the subsequent reactor. Is preferred.

After the desired conversion (65-95%) has been reached, the solvent present and unconverted monomers are removed at high temperature (200-260 ° C.) under vacuum and the resulting polymer is extruded through a die. Cool and cut into desired sized granules. The gaseous product removed under vacuum is concentrated and optionally recycled to the first reactor or to the equipment used to dissolve the rubber and ABS.

The dissolution of the rubber and the preformed ABS resin in the monomer / solvent mixture can be carried out in a single mixer or in two separate mixers. In the latter case, 1
In a first mixer kept at a temperature of 00 ° C. or less, styrene,
Introduce solvent, rubber, and preformed ABS resin,
To the unheated second mixer, add an additional aliquot of the polymerization initiator, acrylonitrile and, optionally, solvent.

The initiator used is a general one usually used for the polymerization of styrene, and is, for example, an organic peroxide radical polymerization initiator. Examples of such initiators include:
Examples include dibenzoyl peroxide, t-butyl peroctanoate, t-butyl perbenzoate, di-tert-butyl peroxide, 1,1′-di-tert-butylperoxycyclohexane and the like. The amount of such initiator added is from 0.005 to 0.5% of the monomer.
5% by weight.

The ABS produced by the method of the present invention comprises:
It consists of rubber particles whose diameter shows a bimodal distribution. By a general method using a transmission electron microscope, the average volume diameter of the first population in this distribution is 0.1 to
It can be seen that the average volume diameter of the second population is 1.5 to 12 micrometers. These particles have a typical cellular morphology in which grafted or ungrafted copolymers are embedded.

The ABS having a bimodal structure of the present invention has physical-mechanical properties such as impact strength at room temperature or below 0 ° C., elongation at break, yield point and breaking load, and tensile modulus. Excellent in balance with high gloss. Due to such properties, ABS produced by the method of the present invention
Is suitable for any application requiring high quality, which is characteristic of the use of ABS obtained by the emulsification method.

[0037]

EXAMPLES In order to gain a better understanding of the present invention and to show embodiments of the present invention, the following non-limiting examples are provided. In the following examples, the following methods were used to evaluate the properties of the obtained copolymer.

Mechanical Properties According to ASTM D256, 3.2 mm thick and 12.
Notched Izod resilience was measured at a temperature of 23 ° C. using a 7 mm sample. The elongation at break and the tensile modulus were measured according to ASTM D638.

Thermal properties According to ISO 306, the Vicat softening temperature was measured at 5 kg in oil.

Rheological Properties The melt flow index (MFI) was measured at 220 ° C. and 10 kg according to ASTM D1238.

Optical properties According to ASTM D523-80, a size of 10 cm
Using a sample of x10 cm x 3 mm, the gloss was measured at an incident angle of 60 ° with respect to this sample. This sample was prepared at 215 ° C using a mold maintained at 35 ° C.
And had a smooth surface with a surface roughness of 0.02. The measurement was performed at a point 3.5 cm from the sample surface opposite to the incident point.

Example 1 (Reference) A mixture comprising the following components was mixed with 1 liter of CF
The mixture was fed to a STR type mixing reactor. (1) 53.5 parts by weight of styrene, (2) 17.8 parts by weight of acrylonitrile, (3) ethylbenzene
20.0 parts by weight, (4) phenolic antioxidant (IR
GANOX 1076) 0.10 parts by weight, (5) peroxide initiator (1,1′-di-tert-butylperoxy-3,3,3)
5-trimethylcyclohexane) 0.02 parts by weight,
(6) Chain transfer agent (t-dodecyl mercaptan)
0.05 parts by weight, (7) polystyrene content is 10
% By weight, polybutadiene content is 90% by weight, polybutadiene calibration gel permeation chromatography
Weight average molecular weight measured by (GPC) is 120,000
(Mark-Houbink constant: k = 3.9 × 1)
0 ^-4 , and a = 0.713), polystyrene calibration GPC
Weight average molecular weight of the polystyrene block measured by the method described above is about 20,000 (Mark-Houbink constant: k
= 1.5 × 10 ^-4 and a = 0.7) 8.70 parts by weight of a polystyrene-polybutadiene linear diblock copolymer.

The resulting mixture was used in a 2 liter volume,
At the top of a vertical, tubular first plug flow reactor with a length / diameter ratio of 7.4, a temperature of 99 ° C. and a flow rate of 0.65
kg / h.

The reactor was divided into two reaction zones, and each zone was thermostat-controlled in order to maintain the temperature of the reaction mixture according to the following temperature profile. First zone: 99 ° C. Second zone: 104 ° C. The reactor was fitted with a stirrer consisting of 20 horizontal arms rotating at a speed of 100 rpm. The reactor pressure was 4 bar.

The residence time of the reaction mixture in the first zone of the first reactor was about 85 minutes, while the total residence time was about 2.8 hours.

0.06 parts by weight of n-dodecyl mercaptan was added to the reaction mixture which had a solids content of about 33% by weight and was continuously discharged from the reactor. This was fed to a second, tubular reactor of the same vertical shape as the first reactor and thermostated to maintain the temperature of the reaction mixture according to the following temperature profile. First zone: 125 ° C. Second zone: 160 ° C. The residence time of the reaction mixture in the second reactor is about 2.8
It was time.

The solids content of the reaction product mass at the outlet of the second reactor was about 70% by weight. This is about 8 conversions
This corresponds to 5% by weight.

Thereafter, the reaction product mass was heated to 250 ° C. in a preheater, and the solvent and the unconverted monomer were devolatilized in an evaporator under a reduced pressure of 40 mmHg.

The content of all volatile components in the ABS discharged from the evaporator was about 0.3% by weight. Table 1 shows the characteristics of the ABS.

Example 2 8.7 parts by weight of the diblock copolymer was replaced by 7.75 parts by weight of the same copolymer, 53.5 parts by weight of styrene was replaced by 51.6 parts by weight of styrene, and acrylonitrile 1
The same procedure as in Example 1 was repeated, except that 7.8 parts by weight was replaced by 17.2 parts by weight of acrylonitrile. Furthermore, as a preformed ABS copolymer, commercially available “SINKRAL X2
002M "was introduced in an amount of 3.45 parts by weight.

Chain transfer agent (t-dodecyl mercaptan)
Was reduced from 0.05 to 0.04 parts by weight.
The weight ratio of (small particle rubber) / (large particle rubber) of the final product was 95.1 / 4.9.

The properties of the product thus obtained are
It is shown in Table 1.

Example 3 8.7 parts by weight of the diblock copolymer was replaced by 7.25 parts by weight of the same copolymer, 53.5 parts by weight of styrene was replaced by 50.6 parts by weight of styrene, and acrylonitrile 1
The same procedure as in Example 1 was repeated, except that 7.8 parts by weight was replaced by 16.9 parts by weight of acrylonitrile. Furthermore, as a preformed ABS copolymer, "SINKRAL X2002M"
Was introduced in an amount of 5.25 parts by weight.

Chain transfer agent (t-dodecyl mercaptan)
Was reduced from 0.05 to 0.035 parts by weight. The weight ratio (small particle rubber) / (large particle rubber) of the final product was 92.3 / 7.7.

The properties of the product thus obtained are
It is shown in Table 1.

Example 4 8.7 parts by weight of the diblock copolymer were replaced by 5.35 parts by weight of the same copolymer, 53.5 parts by weight of styrene were replaced by 46.8 parts by weight of styrene and acrylonitrile 1
The same procedure as in Example 1 was repeated, except that 7.8 parts by weight was replaced by 15.6 parts by weight of acrylonitrile. Furthermore, as a preformed ABS copolymer, "SINKRAL X2002M"
Was introduced in an amount of 12.25 parts by weight.

Chain transfer agent (t-dodecyl mercaptan)
Was reduced from 0.05 to 0.025 parts by weight. The weight ratio (small particle rubber) / (large particle rubber) of the final product was 79.2 / 20.8.

The properties of the product thus obtained are
It is shown in Table 1. Table 1 Example 1 2 3 4 MFI (g / 10 min) 8.5 9.2 9.5 10.0 Vicat softening temperature (° C) 103 103 103 103 Tensile properties Elongation at break (%) 8.0 13.0 15.0 20.0 Modulus of elasticity (N / mm ² ) 2600 2500 2550 2500 Izod resilience 1/8 second, 23 ° C (J / m) 70 190 180 140 1/2 second, 23 ° C (J / m) 105 230 210 175 Gloss (60 °) (%) 95 90 90 80 Volume diameter (*) Small particle diameter (μ) 0.26 0.26 0.27 0.3 Large particle diameter (μ)-6.0 6.0 6.0 (*) The average volume diameter of rubber particles is a thin layer obtained by TEM (transmission electron microscope). It was measured by photograph.

Examples 5 and 6 (comparative) The materials of Examples 2 and 3 are melt-mixed, ie the material of Example 1 and the resin "SINKRALX2002M" at 230 ° C. in a twin screw extruder of the Baker-Perkins type. And obtained by mixing. A SAN resin (styrene-acrylonitrile) "KOSTIL B25 / 5", a product of the present applicant, was also added to the mixture in a fixed amount to control the quantitative ratio of the particle distribution.

The weight ratio of (small particle rubber) / (large particle rubber) of the final product was 95/5 and 92, respectively.
/ 8.

The properties of the product thus obtained are
It is shown in Table 2. Table 2 Example 56 MFI (g / 10 min) 9.5 10.5 Vicat softening temperature (° C) 103 103 Tensile properties Elongation at break (%) 18.0 25.0 Modulus of elasticity (N / mm ² ) 2500 2500 Izod resilience 1/8 second, 23 ° C (J / m) 160 155 1/2 second, 23 ° C (J / m) 200 175 Glossiness (60 °) (%) 88 85 Volume diameter (*) Small particle diameter (μ) 0.26 0.26 Large particle 5.6 5.6 (*) The average volume diameter of the rubber particles was measured from a thin-layer photograph obtained with a TEM (transmission electron microscope).

Table 3 shows the composition of the mixture supplied to the extractor. Table 3 Example 5 6 ABS of Example 1 (%) 90 85 SINKRAL X2002M (%) 5 7.5 KOSTIL B25 / 5 (%) 5 7.5

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Roberto, Notch Italy Virgilio, Via, Chisa, 86 / ti

Claims (6)

[Claims] 1. A method for producing ABS, comprising the following steps a), b), c), d) and e), wherein the size of rubber particles contained in the polymer matrix shows a multimodal distribution. a) a step of preparing a solution comprising a SB type biblock linear rubber dissolved in a monomer mixture comprising styrene and acrylonitrile, b) rubber particles contained in a polymer matrix,
Supplying at least one preformed ABS resin having an average volume diameter greater than 1.5 micrometers to the solution of step (a); c) adding the preformed ABS resin to the solution of step (a) Dissolving; d) continuously feeding the solution thus obtained to a polymerization reactor for ABS resin; and e) polymerizing the final solution to produce an ABS having a multimodal morphology. Process. 2. A two-block linear rubber having an average molecular weight (Mw) of 5,000 wherein S is obtained from an aromatic vinyl monomer.
Of the SB type, wherein B represents an elastomeric polymer block having an average molecular weight (Mw) of 2,000 to 250,000 obtained from a conjugated diene; The method of claim 1, wherein 3. The amount of the S block is 5 to 1 of the entire SB rubber.
3. The method according to claim 2, which is 5% by weight. 4. The method according to claim 1, wherein the preformed ABS resin is added so that the amount of the preformed ABS resin is 0.5 to 15% by weight of the final product. the method of. 5. The preformed ABS resin is obtained by polymerization by a continuous bulk method or a bulk suspension method, and has a rubber phase content of 20% by weight or more.
MFI (ASTM D) measured at 0 ° C./10 kg
1238) is 5 g / 10 min or more, and 12.7 m
m impact strength (ASTM D25
The method according to any one of the preceding claims, wherein 6) is at least 80 J / m. 6. An ABS resin obtained by the method according to claim 1, wherein the size of rubber particles contained in the polymer matrix shows a multimodal distribution.